SATA : Computer Hardware Buyers’ Glossary

SATA (Serial ATA)
pronounced say-tah or sometimes
pronounced to rhyme with santa. This is the faster
successor to the older ATA (Advanced Technology Attachment)
IDE (Integrated Drive Electronics) drives, now called PATA (Parallel ATA)
SATA-1 transfers 150
megabytes per second. SATA2
transfers 3 GBits/Sec. SATA
3 transfers 6 GBits/Sec. And now we have 16 GBits/Sec. The term SATA
-3 is confusing, do they mean 6 Gb/s SATA-3 or 3 Gb/s SATA-2? The trend is
to specify the speed. To use 6 Gb/s
SATA you need your
controller and hard disk to be 6 Gb/s
SATA. If you mix slow and
fast SATA controllers and drives
it works, but runs at the slow speed.

SATA drops the shared bus of
PATA, giving each device a
dedicated cable and dedicated bandwidth. SATA
cables are narrow with only 7 conductors. Oddly the
delicate SATA
power connectors have a whopping 15 pins, to deliver
3.3V, 5V and 12V.

You might wonder why a serial connection would be faster than a parallel one. Does
not parallel have more wires to transfer data? Yes, they it does, but the signals all
must arrive at exactly the same time. To ensure that, they slow down the rate of
signalling.